Smith,H.M. & Taylor,E.H. 1950. An annotated checklist and key to the reptiles of Mexico exclusive of the snakes. Bull. US Natl. Mus. 199: 1-253 - get paper here

Taylor, E. H. 1936. A taxonomic study of the cosmopolitan lizards of the genus Eumeces with an account of the distribution and relationship of its species. Univ. Kansas Sci. Bull. 23 (14): 1-643 [1935] - get paper here